LG KE820 Service Manual page 109

5. Trouble shooting
5.12.12 Checking PAM Control Signals
NC3
20
NC2
15
NC1
10
LB_RFOUT
12
HB_RFOUT
18
Checking Points
VSUPPLY
LB_RFIN
7
U401 VRAMP
6
VMODE
RF3158
5
VBATT
4
TX_EN
3
BAND_SEL
2
HB_RFIN
1
Figure 26. PAM Control Signals Circuit
Figure 27. Transceiver Output
MODE MODE
GMSK LOW
8PSK HIGH
Table 4. PAM Mode Operation
C401 C402 C409 C403
100p 100p 100p 100p
C408 C414
33u
27p
PA_LEVEL
Ramp Burst Control
Control Amp bias
- 110 -
LBAND_PAM_IN
R407
PA_LEVEL
0
MODE
TXON_PA
PA_BAND
HBAND_PAM_IN
MODE
PA LEVEL
TXON PA
TXON_PA
HIGH
HIGH